diff --git a/backend/crates/providers/openai/src/transport/request.rs b/backend/crates/providers/openai/src/transport/request.rs
index d36d43fe3..5f0ed91e7 100644
--- a/backend/crates/providers/openai/src/transport/request.rs
+++ b/backend/crates/providers/openai/src/transport/request.rs
@@ -26,6 +26,7 @@ const TURN_ID_CLIENT_METADATA_KEY: &str = "turn_id";
 const THREAD_SPAWN_SUBAGENT_KIND: &str = "thread_spawn";
 const THREAD_SPAWN_CONVERSATION_PREFIX: &str = "thread-spawn:";
 const ENVIRONMENT_CONTEXT_CONTENT_KIND: &str = "environments.environment_context";
+const DESKTOP_TIME_CONTEXT_CONTENT_KIND: &str = "additional_content.codex_apps_client_time_context";
 
 const CROSS_ACCOUNT_IDENTITY_KEYS: &[&str] = &[
     "authorization",
@@ -130,14 +131,14 @@ pub(crate) fn align_structured_location_fields(
     now: DateTime<Utc>,
     location: &CodexRequestLocation,
 ) {
-    // 只改写完整环境上下文的日期和时区；epoch 时间戳保持绝对时间原值
+    // 环境与 Desktop 时间上下文使用同一位置；epoch 时间戳保持绝对时间原值
     let current_date = now
         .with_timezone(&location.timezone)
         .format("%Y-%m-%d")
         .to_string();
     if let Some(input) = body.get_mut("input").and_then(Value::as_array_mut) {
         for item in input {
-            align_environment_context(item, &current_date, location.timezone.name());
+            align_time_context(item, &current_date, location.timezone.name());
         }
     }
     if let Some(tools) = body.get_mut("tools").and_then(Value::as_array_mut) {
@@ -147,13 +148,19 @@ pub(crate) fn align_structured_location_fields(
     }
 }
 
-fn align_environment_context(item: &mut Value, current_date: &str, timezone: &str) {
+fn align_time_context(item: &mut Value, current_date: &str, timezone: &str) {
     let Some(item) = item.as_object_mut() else {
         return;
     };
-    if item.get("role").and_then(Value::as_str) != Some("user") {
-        return;
-    }
+    // Desktop 将客户端时间放入独立 developer 上下文，不能只覆盖执行环境的 user 消息
+    let (context_tag, content_kind) = match item.get("role").and_then(Value::as_str) {
+        Some("user") => ("environment_context", ENVIRONMENT_CONTEXT_CONTENT_KIND),
+        Some("developer") => (
+            "codex_apps_client_time_context",
+            DESKTOP_TIME_CONTEXT_CONTENT_KIND,
+        ),
+        _ => return,
+    };
     let content_kinds = item
         .get("internal_chat_message_metadata_passthrough")
         .and_then(Value::as_object)
@@ -169,10 +176,10 @@ fn align_environment_context(item: &mut Value, current_date: &str, timezone: &st
         return;
     };
     for (index, part) in content.iter_mut().enumerate() {
-        // 官方自定义 Provider 会移除内容分类，缺省时仍按完整环境上下文识别
+        // 官方自定义 Provider 会移除内容分类，缺省时仍按角色与完整上下文识别
         // 已有分类保持权威，不能覆盖显式标为普通文本或其他上下文的内容
         if let Some(kinds) = &content_kinds
-            && kinds.get(index).and_then(Option::as_deref) != Some(ENVIRONMENT_CONTEXT_CONTENT_KIND)
+            && kinds.get(index).and_then(Option::as_deref) != Some(content_kind)
         {
             continue;
         }
@@ -185,21 +192,27 @@ fn align_environment_context(item: &mut Value, current_date: &str, timezone: &st
         let Some(Value::String(text)) = part.get_mut("text") else {
             continue;
         };
-        if let Some(aligned) = aligned_environment_context(text, current_date, timezone) {
+        if let Some(aligned) = aligned_time_context(text, context_tag, current_date, timezone) {
             *text = aligned;
         }
     }
 }
 
-fn aligned_environment_context(text: &str, current_date: &str, timezone: &str) -> Option<String> {
+fn aligned_time_context(
+    text: &str,
+    context_tag: &str,
+    current_date: &str,
+    timezone: &str,
+) -> Option<String> {
     let trimmed = text.trim();
-    if !trimmed.starts_with("<environment_context>") || !trimmed.ends_with("</environment_context>")
+    if !trimmed.starts_with(&format!("<{context_tag}>"))
+        || !trimmed.ends_with(&format!("</{context_tag}>"))
     {
         return None;
     }
     let document = Document::parse(text).ok()?;
     let root = document.root_element();
-    if !root.has_tag_name("environment_context") {
+    if !root.has_tag_name(context_tag) {
         return None;
     }
     let mut replacements = root
diff --git a/backend/crates/providers/openai/tests/provider/contract/mod.rs b/backend/crates/providers/openai/tests/provider/contract/mod.rs
index f070bf76f..5ab0c07b7 100644
--- a/backend/crates/providers/openai/tests/provider/contract/mod.rs
+++ b/backend/crates/providers/openai/tests/provider/contract/mod.rs
@@ -775,7 +775,9 @@ async fn selected_proxy_location_overrides_global_and_reloads_without_mutating_c
     let original = json!({"model":"gpt-5.4", "input":[
         {"role":"user", "content":[{"type":"input_text", "text":"<environment_context><timezone>UTC</timezone></environment_context>"}], "internal_chat_message_metadata_passthrough":{"content_item_kinds":["environments.environment_context"], "create_time":1789293131.822}},
         {"role":"user", "content":[{"type":"input_text", "text":"<environment_context><timezone>UTC</timezone></environment_context>"}], "internal_chat_message_metadata_passthrough":{"content_item_kinds":["user.text"]}},
-        {"role":"user", "content":[{"type":"input_text", "text":"<environment_context><timezone>UTC</timezone></environment_context>"}]}
+        {"role":"user", "content":[{"type":"input_text", "text":"<environment_context><timezone>UTC</timezone></environment_context>"}]},
+        {"role":"developer", "content":[{"type":"input_text", "text":"<codex_apps_client_time_context><timezone>UTC</timezone></codex_apps_client_time_context>"}], "internal_chat_message_metadata_passthrough":{"content_item_kinds":["additional_content.codex_apps_client_time_context"]}},
+        {"role":"developer", "content":[{"type":"input_text", "text":"<codex_apps_client_time_context><timezone>UTC</timezone></codex_apps_client_time_context>"}]}
     ], "tools":[{"type":"web_search"}]});
     let operation = Operation::Generate(GenerateRequest::from_protocol_payload(
         ProtocolPayload::json_object("openai", original.as_object().unwrap().clone())
@@ -800,6 +802,8 @@ async fn selected_proxy_location_overrides_global_and_reloads_without_mutating_c
         assert_eq!(body.pointer("/input/0/content/0/text"), Some(&json!(format!("<environment_context><timezone>{expected}</timezone></environment_context>"))));
         assert_eq!(body.pointer("/input/1/content/0/text"), original.pointer("/input/1/content/0/text"));
         assert_eq!(body.pointer("/input/2/content/0/text"), body.pointer("/input/0/content/0/text"));
+        assert_eq!(body.pointer("/input/3/content/0/text"), Some(&json!(format!("<codex_apps_client_time_context><timezone>{expected}</timezone></codex_apps_client_time_context>"))));
+        assert_eq!(body.pointer("/input/4/content/0/text"), body.pointer("/input/3/content/0/text"));
         assert_eq!(body.pointer("/input/0/internal_chat_message_metadata_passthrough/create_time"), Some(&json!(1789293131.822)));
     }
     assert_eq!(first_proxy.received_requests().await.unwrap().len(), 2);
@@ -1879,7 +1883,7 @@ async fn provider_should_send_the_request_snapshot_location_to_the_upstream() {
 }
 
 #[tokio::test]
-async fn provider_should_override_unclassified_environment_timezone_over_websocket() {
+async fn provider_should_override_unclassified_time_contexts_over_websocket() {
     let store = Arc::new(MemoryAccountStore::default());
     create_account(&store, "acct_provider_contract").await;
     let listener = TcpListener::bind("127.0.0.1:0").await.expect("listener");
@@ -1896,11 +1900,15 @@ async fn provider_should_override_unclassified_environment_timezone_over_websock
         body
     });
     let environment = "<environment_context><cwd>/home/example/项目</cwd><timezone>Asia/Shanghai</timezone></environment_context>";
+    let desktop = "<codex_apps_client_time_context><timezone>Asia/Shanghai</timezone></codex_apps_client_time_context>";
     let payload = ProtocolPayload::json_object(
         "openai",
         json!({
             "model": "gpt-5.4",
-            "input": [{"type": "message", "role": "user", "content": [{"type": "input_text", "text": environment}]}],
+            "input": [
+                {"type": "message", "role": "user", "content": [{"type": "input_text", "text": environment}]},
+                {"type": "message", "role": "developer", "content": [{"type": "input_text", "text": desktop}]}
+            ],
             "tools": [{"type": "web_search"}]
         }).as_object().expect("request object").clone(),
     )
@@ -1920,6 +1928,10 @@ async fn provider_should_override_unclassified_environment_timezone_over_websock
         event.expect("successful websocket response");
     }
     let body = server.await.expect("server");
+    assert_eq!(
+        body.pointer("/input/1/content/0/text"),
+        Some(&json!(desktop.replace("Asia/Shanghai", "Pacific/Auckland")))
+    );
     assert_eq!(
         body.pointer("/input/0/content/0/text"),
         Some(&json!(
diff --git a/backend/crates/providers/openai/tests/transport/request.rs b/backend/crates/providers/openai/tests/transport/request.rs
index 75539e85d..70828b34f 100644
--- a/backend/crates/providers/openai/tests/transport/request.rs
+++ b/backend/crates/providers/openai/tests/transport/request.rs
@@ -158,6 +158,102 @@ fn encoder_should_align_official_environment_context_without_content_kinds() {
     }
 }
 
+#[test]
+fn encoder_should_align_desktop_time_context_with_environment_dates() {
+    // Desktop Core 0.162.0-alpha.17.2 的应用附加上下文使用 developer role
+    let desktop = " <codex_apps_client_time_context><timezone>Asia/Shanghai</timezone>\n\
+        <current_date>2020-01-01</current_date>\n\
+        Use this client time context for user-facing dates, times, and schedules instead of the execution host's timezone and current date.\
+        </codex_apps_client_time_context>\n";
+    let environment = "<environment_context><current_date>2020-01-01</current_date><timezone>Asia/Shanghai</timezone></environment_context>";
+    for kinds in [
+        None,
+        Some(json!([
+            "developer.text",
+            "additional_content.codex_apps_client_time_context"
+        ])),
+    ] {
+        let mut message = json!({
+            "type": "message", "role": "developer",
+            "content": [
+                {"type": "input_text", "text": "Keep Asia/Shanghai in this instruction"},
+                {"type": "input_text", "text": desktop}
+            ],
+            "internal_chat_message_metadata_passthrough": {"create_time": 1789293131.822}
+        });
+        if let Some(kinds) = kinds {
+            message["internal_chat_message_metadata_passthrough"]["content_item_kinds"] = kinds;
+        }
+        let body = json!({"input": [
+            {"role": "user", "content": [{"type": "input_text", "text": environment}]},
+            message
+        ]})
+        .as_object()
+        .expect("request object")
+        .clone();
+        let before = Utc::now()
+            .with_timezone(&New_York)
+            .format("%Y-%m-%d")
+            .to_string();
+        let encoded = encode_generate_request(
+            &request(body.clone()),
+            "gpt-test",
+            Some(&CodexRequestLocation::default()),
+        )
+        .expect("encode Desktop time context");
+        let after = Utc::now()
+            .with_timezone(&New_York)
+            .format("%Y-%m-%d")
+            .to_string();
+        assert!(
+            [before, after].iter().any(|date| {
+                let mut expected = body["input"].clone();
+                expected[0]["content"][0]["text"] = json!(
+                    environment
+                        .replace("2020-01-01", date)
+                        .replace("Asia/Shanghai", "America/New_York")
+                );
+                expected[1]["content"][1]["text"] = json!(
+                    desktop
+                        .replace("2020-01-01", date)
+                        .replace("Asia/Shanghai", "America/New_York")
+                );
+                encoded.body().get("input") == Some(&expected)
+            }),
+            "both time contexts must agree while preserving other content and metadata"
+        );
+        let unchanged = encode_generate_request(&request(body.clone()), "gpt-test", None)
+            .expect("encode without override");
+        assert_eq!(unchanged.body().get("input"), body.get("input"));
+    }
+}
+
+#[test]
+fn encoder_should_preserve_text_outside_desktop_time_context() {
+    let desktop = "<codex_apps_client_time_context><timezone>Asia/Shanghai</timezone><current_date>2020-01-01</current_date></codex_apps_client_time_context>";
+    let input = json!([
+        {"role": "user", "content": [{"type": "input_text", "text": desktop}]},
+        {"role": "assistant", "content": [{"type": "output_text", "text": desktop}]},
+        {"type": "function_call_output", "call_id": "synthetic", "output": desktop},
+        {"role": "developer", "content": [{"type": "input_text", "text": desktop}], "internal_chat_message_metadata_passthrough": {"content_item_kinds": ["user.text"]}},
+        {"role": "developer", "content": [{"type": "input_text", "text": desktop}], "internal_chat_message_metadata_passthrough": {"content_item_kinds": ["environments.environment_context"]}},
+        {"role": "developer", "content": [{"type": "input_text", "text": desktop}], "internal_chat_message_metadata_passthrough": {"content_item_kinds": []}},
+        {"role": "developer", "content": [{"type": "input_text", "text": format!("Example:\n{desktop}")}]},
+        {"role": "developer", "content": [{"type": "input_text", "text": format!("{desktop}\nKeep this example")}]},
+        {"role": "developer", "content": [{"type": "input_text", "text": "<codex_apps_client_time_context><timezone>Asia/Shanghai</codex_apps_client_time_context>"}]},
+        {"role": "developer", "content": [{"type": "input_text", "text": "<other_context><timezone>Asia/Shanghai</timezone></other_context>"}]},
+        {"role": "developer", "content": [{"type": "output_text", "text": desktop}]},
+        {"role": "developer", "content": [{"type": "input_text", "text": "<codex_apps_client_time_context><example><timezone>Asia/Shanghai</timezone><current_date>2020-01-01</current_date></example></codex_apps_client_time_context>"}]}
+    ]);
+    let encoded = encode_generate_request(
+        &request(Map::from_iter([("input".to_owned(), input.clone())])),
+        "gpt-test",
+        Some(&CodexRequestLocation::default()),
+    )
+    .expect("encode without changing unrelated content");
+    assert_eq!(encoded.body().get("input"), Some(&input));
+}
+
 #[test]
 fn encoder_should_preserve_classified_text_and_non_user_environment_items() {
     let environment =
diff --git a/deploy/README.md b/deploy/README.md
index f9ebcd4f2..8a5c3bf3a 100644
--- a/deploy/README.md
+++ b/deploy/README.md
@@ -363,10 +363,10 @@ OpenAI OAuth 账号的上游传输方式默认 WS；固定为 SSE 的账号不
 代理位置优先。`host.timezone` 控制部署日历和管理端时间展示，不代替请求位置设置。
 覆盖字段与环境消息识别条件见 [代理位置合同](../docs/api.md#独立代理管理--managed-proxies)
 
-Codex 回答仍显示本机时区时，先核对请求是否使用了预期账号和代理，再区分环境正文与工具结果：
+Codex 回答仍显示本机时区时，先核对请求是否使用了预期账号和代理，再区分时间上下文与工具结果：
 
 - 使用新会话询问环境上下文中的时区，避免已有工具输出或历史回答影响判断
-- 检查实际环境消息是否满足完整上下文形状；显式普通文本分类或非法 XML 不会被覆盖
+- 检查 `environment_context` 和 Desktop 的 `codex_apps_client_time_context` 是否满足[时间上下文识别条件](../docs/api.md#独立代理管理--managed-proxies)；显式普通文本分类或非法 XML 不会被覆盖
 - 若模型调用 `date` 等工具查询本机，工具结果仍反映真实系统时区，覆盖不会修改客户端操作系统
 
 网关的请求头画像和位置覆盖不提供完整匿名化。正文与工作区 metadata 的保留范围见
diff --git a/docs/api.md b/docs/api.md
index 9d23782d7..313dd40ed 100644
--- a/docs/api.md
+++ b/docs/api.md
@@ -770,13 +770,19 @@ API 的 `autoLocation` 默认为 `false`；开启时使用已检测位置，测
 关联账号的 OpenAI/Codex Responses 请求（HTTP/SSE、WebSocket）优先使用代理位置，否则使用全局
 运行设置中已开启的 `requestLocation`；两者均未开启时保留客户端原有位置和时区。全局覆盖按请求冻结，
 新请求使用保存后的设置，无需重启；代理覆盖在每次执行时读取，
-换号或换出口按该次选定账号解析。位置只影响环境上下文日期/时区和 Web Search 的结构化位置，
+换号或换出口按该次选定账号解析。位置只影响客户端时间上下文的日期/时区和 Web Search 的结构化位置，
 不改变 epoch 时间戳、真实出口 IP、服务或管理端时区、数据驻留约束及 xAI 请求
 
-环境消息要求 `role: "user"`，文本块为 `type: "input_text"`，完整文本去除首尾空白后由
-`<environment_context>` 与 `</environment_context>` 包围且为合法 XML；只替换根节点直属的
-`current_date` 和 `timezone`。有 `internal_chat_message_metadata_passthrough.content_item_kinds` 数组时，
-仅处理对应分类为 `environments.environment_context` 的文本块；没有分类时，按完整环境上下文识别。
+时间上下文支持以下两种消息，文本块均为 `type: "input_text"`：
+
+| 消息角色 | 完整 XML 根标签 | 内容分类 |
+| --- | --- | --- |
+| `user` | `environment_context` | `environments.environment_context` |
+| `developer` | `codex_apps_client_time_context` | `additional_content.codex_apps_client_time_context` |
+
+文本去除首尾空白后须由对应标签完整包围且为合法 XML，只替换根节点直属的 `current_date` 和 `timezone`。
+有 `internal_chat_message_metadata_passthrough.content_item_kinds` 数组时，文本块的对应分类须匹配上表；
+没有分类时，按消息角色和完整 XML 识别。
 显式标为 `user.text` 或其他分类的内容、普通聊天中引用的示例、工具结果及无法解析的上下文保持原样。
 客户端实际本机时区不受影响，工具读取本机时区后的输出仍可包含真实值；排查见
 [时区与客户端环境信息](../deploy/README.md#时区与客户端环境信息)